Enderdragon

Enderdragons are giant mobs that live in the End. They gain power from the Ender Crystal Towers and occasionally shoot Ender Acid at enemies. In SuperMarioGlitchy4 bloopers, the Chinese Dudes refer to the Dragon as a "Demon of the Underworld", and the End as "Underworld". Ender Dragons are the first boss mobs to be introduced in Minecraft (one per save file or 'world', but this was changed in 1.10) , next is the Wither Boss (which can be battled an infinite amount of times and even multiple at a time)

Ender Dragons appear in the blooper Befriend the End, where Smg4, Mario, and Starman3 find the magic orb (wich used the sprite of the red orb from Pokémon Ruby and Sapphire) dropped by the Chinese Dudes and accidently travel to the End. They meet Endermen and other creatures, but they find out they need to escape when the Ender Dragon chases them. They get help from a old tramp and try to use the orb to get back, but the Ender Dragon knocks it into nothingness. Then it calls many other relative Ender Dragons to attack them. Luckily the Chinese Dudes arrive and freeze time to have the trio escape, but Mario, being a fool, presses the orb again and they travel back to the End... with the 1.000.000 Ender Dragons stalking them.